change where mini gets tuner from

I have a roamio that is on my main tv. Hardwired internet with moca enabled and working. I have a Xl4 that is in the bedroom working and connected using the moca. My mini is using a tuner from the roamio and i want it to use one from the XL4. When I go to through the setup on the mini the XL4 is not available to use as a tuner for live tv. Only gives the roamio as an option, xl4 is seen but not available. Does that unit also have to be hardwired to my router or should i be able to use the mini with just moca.
I can play stuff from either unit.